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'We're not saying the sky is about to fall in'. Yes you are, a bit

Despite all this, the RAE report also says:

Erroneous GPS signals in an urban area could cause road accidents whilst disrupting the dispatch and navigation of emergency vehicles and causing their communications systems to fail [several days later, it would seem].

Again, this is scary stuff. The lead author of the report, Dr Martyn Thomas, tells the BBC that "We're not saying that the sky is about to fall in; we're not saying there's a calamity around the corner," but he sort of is, actually.

We put this to Ploszek, who said: "Satnav errors can have effects on the situational awareness of drivers and mariners."

Nonetheless we should probably bear in mind here that GPS gets jammed and/or spoofed all the time already, without any of the disasters that the RAE report predicts:

In the USA, the JLOC network has been established to detect jamming nationwide. They are currently registering thousands of incidents of jamming each day – many of them legitimate use by authorised agents**.

Ploszek adds however that if and when location-based road charging comes in, the scope for jamming will increase and nuisance/outages will rise with it unless the system is set up correctly.

Even so it's hard to imagine how eLORAN would help. We might consider that one of the authors of the RAE report is from the GLAs, with a conflict of interest over eLORAN – which might explain why the document mentions timing-signal vulnerabilities and pushes eLORAN repeatedly but doesn't mention the MSF signal at all. The fact that useful checks and backups for satnav position errors already exist – cell location, inertial etc – is mentioned but only in order to say that eLORAN would be better, at least at sea.

Comment

So: this report is definitely incomplete and, bluntly, has strayed into scaremongering territory.

There are surely some grounds for concern at the increasing use of satnav technology - nobody would deny that. As Ploszek and the RAE say, it is certainly unwise to build hardware which relies solely on GPS, whether for position or timing - and it's madness to do so when the kit in question is going to be used as a backup for GPS, as in the case of marine radar (this is apparently quite common nowadays).

But many backups and checks already exist that could be incorporated into equipment today: the case for more government funded infrastructure in general is unproven. The existing eLORAN station, whose signals reach well beyond the shores of the UK, already solves the timing-signal issue for applications where the MSF station is unsuitable: there seems no real reason to use it for navigation too, not when backups like radar, cell triangulation and inertial are already present. One of the primary reasons offered by the RAE and the GLAs for eLORAN positioning on top of timing is that it will permit such applications as road charging and prisoner tracking to work better - but many people would question whether this actually strengthens the case for eLORAN.

People often forget, as well, that GPS wasn't primarily intended for air or surface navigation, or for timing. The primary reason that the USA created it was actually to supplement the inertial guidance of nuclear missiles. As such GPS is a key part of the US nuclear deterrent, which means that the US military and government regarded it – and mostly continue to regard it – as essential to their national survival. It was built, and is maintained, with that in mind.

The chance (for instance) that any future US administration will actually allow GPS worldwide coverage to lapse due to relatively paltry budget issues, as has been speculated in recent times***, is about the same as the chance that the USA will unilaterally disarm itself.

GPS is probably a lot more to be relied upon than people think. ®

Bootnotes

*AIS is nowadays mandatory for ships of any size. It transmits the vessel's identity, position, course and speed data on a VHF band, most of which info it works out using GPS. An AIS receiver can thus plot all nearby ships on a display and tell whether any of them pose a collision risk.

You still need eyeballs and radar because small vessels don't carry AIS. A proper radar can also track contacts and work out their closest-point-of-approach (CPA) just as well as AIS can. (It isn't in the report, but Ploszek tells us that the Pole Star's radar was also reliant on GPS timing - we can certainly agree that nobody should be making or buying radars like that for use on ships).

**One interesting item revealed by the report is that so-called "Blue Team jamming" of GPS is actually quite common, both in the USA and UK. We learn:

Blue Team Jamming [where Blue Team is a generic term for "friendly forces"] is deliberate – generally to defeat a perceived threat of covert tracking. It will probably be low power and have a similar impact to criminal jamming. However there would be an impact if they [who?] parked for long periods near critical infrastructure which used GPS timing.

One might suggest that officially sanctioned GPS interference would also be a likely tactic against a perceived threat from improvised drone missiles, relatively easily made by adding an explosive payload to a commercially available GPS-guided UAV. This threat is already much bigged-up in security-fear circles.

***By the US Government Accountability Office. This would seem an impeccable source of information, but actually the GAO is surprisingly erratic at times - for instance it recently, nonsensically, asserted that Craigslist and eBay are terrorist arms bazaars.

Lewis Page was a Royal Navy officer from 1993 to 2004. He served as navigator (and precise-navigation officer, necessary aboard mine countermeasures ships) during the days when civil GPS was degraded and p-code or differential GPS weren't commonly offered to the minewarfare community. As such he often had to use various recondite and unreliable nav technologies including Decca, Hyperfix, Microfix etc. He also spent much time asking people what the hell spheroid and datum their lat/long coordinates were on, usually without getting an answer. Then he would be blamed for the fact that the reported thingy on the seabed could not be found. It was all most unfair.